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Today for the first time ever I captured a 4K resolution picture. I don't know much about cameras or photography but I expected the picture to at least be sharp like usually high resolution pictures are.

But when I zoom in it gets pixelated. I would assume the total opposite. I thought a 4K picture would provide much better zoom capability than a standard DSLR picture or even a mobile phone picture for that matter. If I zoom in on that picture it looks like it was taken using a 10-year-old mobile phone.

What is wrong with what I am expecting or doing? I don't know how to explain the disappointment, but I do know that it's me missing something.

I am looking at the pic at 1600×900 resolution on a 17-inch notebook, if that matters. The picture itself is 3840×2160.

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    Can you provide a link to the picture? This can be any number of issues, but the most likely issue is probably related to how the image has been compressed. – Chris Stillwell Jul 18 '16 at 18:31
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    what camera? what lens? what is a 4k picture? 4k is video. As far as i can tell a 4k camera takes 4k video not 4k stills. ?? – Alaska Man Jul 18 '16 at 18:37
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    @Alaskaman that's true. It's almost funny that i missed that difference. Guess i need some sleep :) – Hanky Panky Jul 18 '16 at 19:06
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    Many of the 2K and 4K images you see broadcast are shot with really good lenses and excellent lighting. – Blrfl Jul 19 '16 at 13:29
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    What did you take a picture of? Maybe you need a more interesting subject, or framing, etc. (+1 to the other answers and comments about how a photo at that resolution is not otherwise novel or exciting). – WBT Jul 19 '16 at 21:03
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4K might be the next big thing in video, but for still photography that's just 8 megapixels, which is quite low for most cameras, and I think around the resolution of the iPhone. I have a Nikon D5300 with 24MP resolution, and I've seen other DSLRs get up to 36MP or higher.

And no matter what, if you zoom in enough, you will eventually get pixelation (anything over 100% will look blocky), that's just the nature of digital. Make sure that you judge the picture by looking at it from the intended distance and at the intended zoom level. Rarely will you look at a picture at 100% size on a monitor, and prints are typically viewed at a distance, vary rarely will someone take a magnifying glass to it.

It is possible that the .jpg compression is done at a low quality (high compression), which can create blocky artifacts (say 8px by 8px blocks) that look very similar to a pixelated picture. Using less compression (higher quality) will help, but increase the file size (that is the point of jpeg, after all!)

And no resolution will make up for a blurry or out of focus picture. That's often a bigger problem than the megapixel size. The law of diminishing returns really becomes significant as more pixels are crammed onto a sensor.

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    Silly me, now when i look back at it all of it makes so much sense. Thanks! – Hanky Panky Jul 18 '16 at 19:04
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    I remember back in the early 2000's when someone asked on a photo forum when digital cameras would be able to take 'HD' photos. The answer he got was 'Several years ago'. – Steve Ives Jul 19 '16 at 9:55
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    Ssssh, don't mention Hasselblad's studio flagships. hasselblad.com/h6-system/h6d-100c – Crowley Jul 19 '16 at 16:22
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    If >100% zoom looks "blocky" rather than just non-sharp, you have awful software that's treating samples as square "pixels" rather than as sample points for reconstructing a continuous signal. – R.. Jul 19 '16 at 23:11
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    @R.. Well, Window's photo viewer does that, so that going to affect a lot of people. And in any case, it depends what you want. Other interpolation approaches eliminate the blockiness, but softens it considerably, since you're still limited by the information contained in the pixels you have. Personally, if I'm working on a photo and I'm zoomed in a >100%, it's because I want to see the pixels. – pwcnorthrop Jul 20 '16 at 0:52
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Most cameras already have a resolution going far beyond 4K. Assuming you mean Ultra HD (3840x2160) opposed to "true" DCI 4K (4096x2160) you get a resolution of about 8MP (DCI 4K would be about 8.8MP). Most cameras are already way over this size and are at 20MP or even higher. So a "4K" image would actually be smaller than a full size image.

That aside, you still need a picture that's properly focused, shot at a high enough shutter speed as to not be blurry, shot at a low enough ISO to not be grainy etc. Resolution is just a small part of a sharp image.

And even when you have perfect sharpness and no ISO noise you still can't zoom (much) beyond 100% before it starts to become blocky. This is because the moment you start to display 1 pixel as more than one pixel, the software has to interpolate what the pixels mean. This isn't that bad at 2x, 3x etc. magnification because it can just show the pixels as larger pixels. When you are looking at a magnification of 1.5x then it has to show the original pixel, and calculate what the "half" pixel should look like based on the other pixels that contribute to this pixel.

So, if you are looking at the image at 100% it shouldn't be blocky at all. Are you sure you aren't zoomed in beyond 100%?

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    Also - shoot in RAW. JPEG/JPG is a lossy format and uses compression. So your JPG image won't be anywhere near as high quality as a RAW shot. And when you transfer it to a computer, do a straight copy without any import processing at all. An image with 3840x2160 resolution at 300dpi in RAW will be around 18MB in size. The same resolution at 300dpi in JPG will be around 5-7MB in size. The same resolution JPG again but in 96dpi or 72dpi will only be 800-1200kB in size. – Reece Jul 18 '16 at 23:20
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    "The same resolution at 300dpi in JPG will be around 5-7MB in size. The same resolution JPG again but in 96dpi or 72dpi will only be 800-1200kB in size." ??!!??!!??!!?? 3840x2160 pixels is 3840x2160 pixels. The dpi has absolutely NO impact on image file size. Compression ratio does. – Michael C Jul 19 '16 at 5:20
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    @ReeceDodds DPI in JPEG is just a parameter. You can edit it to 1 dpi or to 10000 dpi and it won't change a singe pixel. It's merely a hint about how the file should be zoomed when displayed or printed. – Agent_L Jul 19 '16 at 9:28
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    @ReeceDodds Also the RAW advice is a very bad one, because RAW is not an image at all. It's just a dump of sensor data that requires much work to turn it into a useful image. Unless someone knows how to perform this work, can do it better than the camera and is willing to actually put in the effort, advising to shot RAWs boils down to "make your photos cumbersomely large and unreadable". There is no need for RAWs until the need manifests itself. – Agent_L Jul 19 '16 at 9:29
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    @Agent_L Ufraw lists "Nikon D1" under "Other supported cameras as of today. (Looks like the most recent version is 0.22.) So does Dcraw RCS revision 1.477 date 2016/05/10 which Ufraw is based on. Does that count? – a CVn Jul 20 '16 at 9:33
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Whoever told you about 4K probably mislead you. At least, you have the resolution right. You see, 4K at 3840x2160 is a resolution term used for video, signifying almost 4000 pixels in width. The aspect ratio there is 16:9 which is the same as HD video. Cameras usually shoot 4:3 or 3:2 images, although there are other ratios too.

A pixel is a pixel. There is no reason a 1600x900 image on your display would look any less or more pixelated than a 3200x1800 when zoomed at 100%. The only difference is that you would see only a quarter of the 3200x1800 one. With a 4K image, you see even less of it but each pixel is still a pixel.

Without seeing the image you are actually talking about, I would guess that what you are describing is that it is highly compressed. Maybe it is a frame of 4K video whose quality can vary but is usually not that high because it is designed to save space and only seen during a fraction of the second.

So far this has nothing to do with photography. It is just imagery. If you compare this to a photo taken by a recent digital camera though, you will find that 4K is very low. They do not make any cameras with such low resolution anymore. 16 to 24 MP is the norm now with this being 2-3X the resolution of 4K. There are expensive cameras with up to 100 MP now.

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    Thanks! Very informative. Glad i asked because now i am getting to learn good things – Hanky Panky Jul 18 '16 at 19:22
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Simply put, sensor resolution is a sales gimmic. A tiny little sensor with lots of sites crammed really close together cause noise and bad low light abilities. They start absorbing charge from each other and making artifacts that have to be filtered by software. The bigger the sensor, the bigger the sites, the more sensitive they are and the cleaner the image. A full frame Nikon pro D5 can focus and shoot in light you cannot see in. Next is the lense. Light dispersion at the lens is a big killer of fine resolution. That's why Nikon ED & Canon L lenses that are capable of better resolution than the best cameras cost thousands and weigh pounds.

  • Just a side note: while resolution is used as a marketing gimmick, the sensor technology is getting better, resulting it better images at higher ISOs at same sensor size, OR in an increase in resolution without more noise. but yeah, unfortunately it has become a tool of misleading marketing. – Can Poyrazoğlu Jul 24 '16 at 7:38
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4k is for video, that is quite low for photography nowdays. Video is good at 4k. When taking 4K pictures, use a tripod. Also, beware of the truth of camera specifications. If it is a cheap camera, you have to determine if the manufacturer is using interpolation or exaggerating the specifications.

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First, it depends on what make and model of camera you are using, as '4K photo' modes may work in different ways.

But usually the main reason for using 4K photos is speed. As it essentially recording a video, it is like using a high speed burst mode, at up to 30 frames per second. For many cameras, it is essentially recording a 4K video, then extracting photos from that. So it could allow you to record the exact instant something happens.

As it is based on a 4K video, it will be the same resolution as that. So typically about 4000 pixels wide, at 16:9 ratio. Which gives about an 8 megapixel image.

So yes, this is lower resolution than a single still photo on most cameras. But it is still good enough for many purposes, eg viewing on screen, or sharing on the web. But you may notice the lack of pixels if you zoom in, or if you crop part of the image, or for larger prints. Or if cropped to 4:3 or 3:2 ratio, it would be lower resolution.

Also consider focussing. Is the camera just focussing at the start of the 4K burst? If so, a moving subject may go out of focus. Or is it some sort of continuous focus, which could track moving objects. This may be an option in the camera settings.

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